Various wheels and driving systems therefore have been proposed in the prior art. One such wheel and driving system is disclosed in EP-A-1 350 652, which discloses a motorised driving wheel comprising a circumferential rim defining an axis of revolution. The wheel system further comprises an electrical motor for producing a driving force, the motor comprising an output shaft rotatable around a motor axis. A transmission system is provided for transmitting the driving force from the motor to the circumferential rim. More specifically, the output shaft of the motor is provided with a gearwheel engaging a toothed inner circumferential portion of the wheel, so as to apply the driving force of the motor to the rim for advancing the wheel, the motor axis being substantially parallel to the axis of revolution of the rim. The wheel forms a housing enclosing the motor and a plurality of batteries, which provide electrical power to the motor.
It has been found that such a wheel system suffers from the drawback that the longitudinal dimension of the motor is limited by the width of the wheel, thereby putting an upper limit to the power producable by the motor.